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In this paper, the microstructure evolution and properties of squeeze-cast Al–8Si-1.5Cu–1Ni-0.5Mg-0.5Mn-0.2V-0.2Ti-0.2Zr alloy (hereafter, Al–Si–Cu–Ni alloy for short) were investigated under various solution processes, evaluating the mechanical properties at room and elevated temperatures for both as-cast and T6-treated states. The results showed that following the optimal two-stage solution (i.e., solution at 510 ​°C for 6 ​h ​+ ​solution at 530 ​°C for 8 ​h) and subsequent aging at 190 ​°C for 10 ​h, referred to as the S530-T6 treatment, the Al–Si–Cu–Ni alloy exhibited excellent room/high temperature performance. The ultimate tensile strength (UTS), yield strength (YS) and elongation of the alloy at room temperature were 410 ​MPa, 368 ​MPa and 1.5 ​%, and the UTS, YS and elongation of alloy at 300 ​°C were 177 ​MPa, 170 ​MPa and 6 ​%, respectively. The increase in strength at room temperature is mainly attributed to the spheroidization of eutectic silicon and the precipitate strengthening aroused from uniformly dispersed nano-sized Q-Al 4 Cu 2 Mg 8 Si 7 , σ-Al 5 Cu 6 Mg 2 and θ′-Al 2 Cu phases, while the increase in strength at high temperature is due to the formation of heat-resistant Ni-rich phases and the improvement of the micromorphology of high melting point intermetallic compounds. [ABSTRACT FROM AUTHOR]

Effects of indirect squeeze casting process parameters on the microstructure and mechanical properties of an A356.2 alloy engine hanger were studied. A 4-factor, 4-level orthogonal test was used to study the effects of applied pressure, punch velocity, pouring temperature and mold preheating temperature. The pressure, punch speed, pouring temperature and mold preheating temperature of the optimum process parameters were determined by range analysis (RA) as 100 MPa, 60 mm/s, 700 °C and 200 °C, respectively. The analysis of variance (ANOVA) showed that the only significant factor affecting the microstructure and mechanical properties was pouring temperature, while the other three factors were not significant. The specimens demonstrated mechanical characteristics akin to forged hangers, boasting a tensile strength of 297 MPa, 10.2% post-fracture elongation, and 105 HBW hardness. After T6 heat treatment, except the eutectic silicon morphology changed significantly, the microstructure basically maintained its as-cast characteristics. The samples' microstructure were categorized into three regions: coarse grain α-Al (A), eutectic structure (B), and fine grain structure (C). It was found that elevated pouring temperature could keep the pressure transmission channel open, which was helpful to improve the feeding ability and form a refined grain structure in zone C. However, with the excessive increase in casting temperature, α-Al grains in region A would be coarse, which would lead to the decline of mechanical properties. Therefore, 700 °C was determined as the best pouring temperature. [ABSTRACT FROM AUTHOR]

The influence of the transition alloying element nickel and the alkaline earth element strontium on the microstructure and tensile properties of squeeze cast Al−Si‐Cu alloy under as‐cast condition at elevated temperature of 100 °C, 200 °C and 300 °C is investigated in comparison with the conventional Al−Si‐Cu alloy (A380). Aluminum alloy A380 is alloyed and modified with 2 wt% additional nickel (Ni) and 0.02 wt% strontium (Sr). Squeeze casting is employed to cast the modified A380 under an applied pressure of 90 MPa. The results of tensile testing at the selected elevated temperatures indicate that the Ni and Sr containing A380 alloy exhibits a significantly improvement on tensile properties, specifically ultimate tensile strength and yield strength with 10 %‐30 % increases. The as‐cast microstructures of both the conventional and Ni and Sr‐containing alloys are observed by an optical microscope and further analyzed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of Ni‐containing intermetallic phases with Ni addition, and the modified eutectic Si phase with refined morphologies due to the Sr addition should be responsible for the considerable enhancement on the as‐cast strengths of the squeeze cast Ni‐ and Sr‐containing alloy over those of the conventional A380 alloy. [ABSTRACT FROM AUTHOR]

In this paper, engine flywheel shell components of ZL104 aluminum alloy were formed by squeeze casting forming technology, and the effect of process parameters on mechanical properties and microstructure of the formed parts was investigated. Sixteen sets of orthogonal test schemes are designed according to four conditions of specific pressure, holding time, pouring temperature and mold temperature. After the mechanical properties of the castings under different sets of experimental conditions were analyzed, the optimum process parameters were derived from the comprehensive analysis according to tensile strength and elongation. The optimum process parameters involve a casting temperature of 655 °C, a scheme B mold temperature, a pressure holding time of 20 s and a specific pressure of 34 MPa. The average tensile strength and average elongation of the formed flywheel shell components under the optimum process conditions were 211.2 MPa and 7.7%, respectively. The microstructure of the formed parts is mainly composed of α-Al phase and eutectic silicon phase. When the process parameters are properly selected, high mechanical properties and microstructure with little cast defects were obtained in the parts formed by squeeze casting. Except for Al, Fe, Mn and Si elements are mainly enriched at the grain boundary. [ABSTRACT FROM AUTHOR]

In this study, concurrent enhancements in both strength and ductility of the Al-2Li-2Cu-0.5Mg-0.2Zr cast alloy (hereafter referred to as Al-Li) were achieved through an optimized forming process comprising ultrasonic treatment followed by squeeze casting, coupled with the incorporation of Sc. Initially, the variations in the microstructure and mechanical properties of the Sc-free Al-Li cast alloy (i.e., alloy A) during various forming processes were investigated. The results revealed that the grain size in the UT+SC (ultrasonic treatment + squeeze casting) alloy was reduced by 76.3% and 57.7%, respectively, compared to those of the GC (gravity casting) or SC alloys. Additionally, significant improvements were observed in its compositional segregation and porosity reduction. After UT+SC, the ultimate tensile strength (UTS), yield strength (YS), and elongation reached 235 MPa, 135 MPa, and 15%, respectively, which were 113.6%, 28.6%, and 1150% higher than those of the GC alloy. Subsequently, the Al-Li cast alloy containing 0.2 wt.% Sc (referred to as alloy B) exhibited even finer grains under the UT+SC process, resulting in simultaneous enhancements in its UTS, YS, and elongation. Interestingly, the product of ultimate tensile strength and elongation (i.e., UTS × EL) for both alloys reached 36 GPa•% and 42 GPa•%, respectively, which is much higher than that of other Al-Li cast alloys reported in the available literature. [ABSTRACT FROM AUTHOR]

This research presents a novel approach to overcome the stress shielding effect and non-degradability commonly observed in metallic implants, which often require revision surgery. The study introduces a hybrid metal/ceramic (Ti/HA) reinforcement within the Mg-3Zn binary alloy matrix fabricated using the squeeze casting technique. The alloy matrix incorporates 1 wt% Ti and varying weight percentages (0.5, 1, and 1.5 wt%) of hydroxyapatite (HA). Microstructure analysis revealed significant grain refinement in the alloy upon adding the hybrid reinforcement. Phase analysis using XRD confirmed the presence of Mg-Zn intermetallic phases and corresponding reinforcement phases. Vickers microhardness testing demonstrated a 14.4% (89 HV) increase in hardness for the hybrid composite with 1Ti/1.5HA compared to the unreinforced alloy and other composites. Compressive testing revealed enhanced mechanical properties in the hybrid composites. The 1Ti/1.5 HA hybrid composite displayed a 12% (121 MPa) increase in compressive yield strength (CYS) compared to the alloy, while the 1Ti/1HA hybrid composite exhibited an impressive 22.5% (217 MPa) increment in compressive strength. Corrosion performance evaluation in a phosphate-buffered saline (PBS) environment indicated that the 1Ti/1.5 HA hybrid composites demonstrated comparable corrosion performance to the unreinforced alloy, with a corrosion density of 4.53 × 10−5 μA/cm2 and a linear polarization resistance of 893 ohms. Based on the findings, the Mg-3Zn alloy with 1Ti/1.5 HA hybrid reinforcement emerges as a promising material for load-bearing biodegradable implants. [ABSTRACT FROM AUTHOR]

Semi-solid rheological squeeze forming has distinct advantages over traditional casting and forming techniques. In this study, a high-performance thin-walled CuSn10P1 alloy was successfully produced by combining liquid-metal instantaneous undercooling-induced nucleation, semi-solid slurry homogenization treatment, and semi-solid rheological squeeze forming. The effects of the forming specific pressure (MPa) and filling speed (mm/s) on the microstructure and mechanical properties of these parts were explored in this study, and the influence of the intergranular brittle phase (α-Cu + δ-Cu41Sn11 + Cu3P) content on the mechanical characteristics was determined. CuSn10P1 alloy with a Cu13.7Sn phase exhibiting a large number of spherical or nearly spherical morphological features coexisting with the high-tin solid-solution layer morphology was discovered and prepared at a mold temperature of 485 °C, specific pressure of 165 MPa, and filling speed of 22 mm/s. Parts with this microstructure had excellent mechanical properties, including an ultimate tensile strength of 419.95 MPa, yield strength of 228.89 MPa, and an elongation of 13.71%. This study illustrates the viability of semi-solid rheological squeeze casting for manufacturing high-performance thin-walled high-tin copper alloys. [ABSTRACT FROM AUTHOR]

The performance of industrial tribo-systems depends on advanced composites with superior tribological characteristics. In this study, the CoCrFeMnNi high entropy alloy (HEA) is prepared through mechanical alloying, while stir squeeze casting aided with an ultrasonic transducer is used to fabricate AA 6082 alloy and x% HEA/AA composites (where, x= 2, 4, 6, 8 in weight percentage). The effect of HEAp on dry sliding wear performance of HEA/AA composites is examined in as-cast conditions using a pin-on-disk wear tester at varying normal applied pressure (0.254 MPa, 0.509 MPa, 0.763 MPa, 1.018 MPa, and 1.273 MPa), varying sliding distance (1000 m, 2000 m, 3000 m, 4000 m, and 5000 m) and a constant sliding speed (3.5 m/sec), special emphasis is centered on response factors such as wear rate, seizure resistance, and bulk temperature upsurge. The composite showed an ability to withstand higher temperatures, and better seizure and wear resistance over the alloy. The phase identification and microstructural study were carried out using an X-ray diffractometer, field emission scanning electron microscope, and transmission electron microscope, whereas the topography of worn-out surface was examined through an optical profilometer. There was a substantial decrease in coefficient of friction, and wear rate noticed as the HEAs concentration increased, whereas in all the wear conditions, the wear rate of 8% HEA/AA composite shows maximum resilience against wear, the inclusion of HEA particles also influences the extent of the subsurface at the seizure condition. [ABSTRACT FROM AUTHOR]

The microstructure and compressive properties of the 7xxx series aluminum alloy (Al – 12.44Zn – 3.22Mg – 1.13Cu – 0.19Zr – 0.12Sr) reinforced with SiC whiskers via squeeze casting are investigated after aging treatments T6-1, T6-2, T6I4-1, and T6I4-2. For this purpose, the effect of four kinds of aging heat treatments on the properties of the aluminum metal matrix composites (AMMCs) is studied systematically through Vickers hardness and room temperature compressive testing. The microstructure is analyzed by optical microscopy, scanning electron microscopy, and x-ray diffraction. The experimental results show that the hardness of the AMMCs after four kinds of aging processes has different degrees of improvement compared to no-aging. After the T6-1, T6-2, T6I4-1, and T6I4-2 aging processes, the hardness of the composites is 325, 278, 306, and 345.8 HV, respectively. The additional T6-2 aging treatment provides the highest compressive strength and compressive strain, about 747 MPa and 7%, respectively, as well as a maximum dislocation strengthening of approximately 86.89 MPa. [ABSTRACT FROM AUTHOR]

In this work, squeeze casting experiments of flywheel housing components with a large wall thickness difference and a complex shape were carried out with AlSi9Mg aluminum alloy. The defects, microstructures, and mechanical properties under different process parameters were investigated. Furthermore, the local pressurization process was applied to the thick-walled positions to force-feed the cast defects. The mechanical properties and microstructures at these positions were analyzed. The results showed that the surface quality of formed components was good and that local pressurization could effectively reduce the shrinkage cavity and shrinkage porosity in thick walls, but the scope and effect of forced feeding were limited. The optimum process parameters were a pouring temperature of 650 °C, a specific pressure of 48 MPa, a mold temperature of 220 °C, a local pressurization of 800 MPa, and pressure delay times of 15 s (side A) and 17 s (side B). The ultimate tensile strength, yield strength, and elongation of the formed component under validation experiments of the optimum process parameters were 201 MPa, 103 MPa, and 5.1%. Meanwhile, the fine grains of primary α-Al were mainly rosette and equiaxed grains, and the average grain size was about 40 μm. The microstructure of the eutectic silicon was acicular and was prone to segregation under pressure. According to profile morphology, the positions after pressurization were divided into a deformation zone, a direct action zone, and an indirect action zone. The coexistence of as-cast and plastic deformation microstructures was observed. The effect of local pressurization mainly involved a change in the solidification process, plastic deformation, and forced feeding. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the effect of heat treatment (T6) on the microstructure, mechanical, and corrosion properties of Al 319.0 alloy. In particular, Al 319.0 alloy is developed by squeeze casting using 200 MPa pressure, and further the ingots are solutionized, quenched and artificially aged to develop a homogenous microstructure, improve distribution of secondary phase(s), and mechanical properties at ambient and elevated temperatures. The phase and microstructure of the as-cast and heat-treated Al 319.0 alloys analyzed using X-ray diffraction, optical microscope, and field emission scanning electron microscope illustrate cast ingot contain α-Al as a primary phase and Al2Cu, eutectic Si, and Al5Si7Cu-containing intermetallic as secondary phase(s). However, heat treatment leads to complete dissolution of Al5Si7Cu and partial dissolution and re-precipitation of Al2Cu phase. Moreover, heat treatment changes the morphology of eutectic Si into spheroidal Si, blocky Al2Cu into spheroids Al2Cu, and the heat-resistant α(FeMn), Al8Cu3Mn(Si) phases emerged. The tensile test at room and elevated temperatures exhibit significant improvement in the YS and UTS at ambient temperature in heat-treated alloy owing to the presence of precipitation-hardened phases. Importantly, these phases are found stable up to 150 °C and tend to coarsen at 250 °C owing to thermal softening invariably leading to a substantial reduction in mechanical properties. Potentiodynamic polarization and electrochemical impedance spectroscopy shed light on galvanic corrosion phenomena predominant in 0.1 M NaCl solution. In particular, heat-treated alloy specimens demonstrated the lowest corrosion current (Icorr—~1.72 μA/cm2), and highest polarization resistance (Rp—12260 Ω.cm2) implying superior corrosion resistance as compared to as-cast alloy owing to protective barrier provided by finer Al2Cu precipitates and spheroidal Si. [ABSTRACT FROM AUTHOR]

The present study investigates the effect of wall thickness on the mechanical properties of Al-5Mg-2.2Si-0.6Mn-0.1Ce castings, using squeeze casting to fabricate alloys with varying wall thicknesses. The results show that changes in wall thickness affect defect generation, grain size, and secondary dendrite arm space (SDAS), which in turn influence the tensile properties of the material. Specifically, the shrinkage porosity of the castings decreases gradually with increasing wall thickness, while the SDAS and grain size increase. Although this reduces defects and improves the tensile properties, the increase in SDAS and grain size leads to a decrease in yield strength and tensile strength. Notably, the material's tensile strength reaches its maximum (265.5 MPa) at a wall thickness of 10 mm. These findings demonstrate the importance of optimizing wall thickness parameters for complex castings, with potential implications for industrial production and application. [ABSTRACT FROM AUTHOR]

The study explores the development of novel composites using nano-based hybrid reinforcements to enhance mechanical and wear properties. Specifically, A356 aluminum matrix composites containing a combination of silicon carbide particles (SiCp) and multi-walled carbon nanotubes (MWCNTs) were prepared using the Rotary and Squeeze casting methods. The research aimed to investigate the mechanical properties and microstructure of A356 alloy with varying percentages (5%, 10%, and 15%) of SiC-MWCNT hybrid reinforcements added at a 2:1 ratio. The results indicated that the squeeze casting method led to refined silicon and intermetallic compounds in the microstructure, and the dispersion of SiCp in the A356 alloy was homogeneous. Grain refinement was achieved, with a notable 35.22% improvement compared to the A356 alloy without reinforcements. The addition of SiCp, intermetallics, and Si particles increased tensile and yield strength. The study also observed a reduction in Si phase and α-Al grains with increased squeeze cast parameters. Furthermore, the aspect ratio and mean diameter of Si needles decreased by 31% and 43%, respectively, compared to the base alloy. After the squeeze casting process, improvements in yield strength (17.99%), tensile strength (36.66%), and percentage of elongation (195.91%) were noted compared to the composite prepared by rotary centrifugal casting methods. Lastly, the study evaluated the machinability of the hybrid MMC through an optimization technique, Entropy-PROMETHEE (Entp-PRMT). Overall, the research demonstrates the potential of nano-based hybrid reinforcements and the squeeze casting method to enhance the mechanical properties and microstructure of A356 aluminum matrix composites, offering promising applications in various industries. [ABSTRACT FROM AUTHOR]

The piston in the automobile engine must withstand high stress and temperatures and also have low weight. The alloy of Al-Si is the most commonly used in the piston. The reinforcement using ceramics, fibres or nanoparticles will increase the properties of the piston alloy. In this work, the piston alloy is fabricated as a metal matrix composite of Al-Si reinforced by TiC-MoS2 using the squeeze casting method. The squeeze casting effect on the matrix and the reinforcement is studied using tensile testing and microstructure analysis. The strength hardness obtained from the experimentation gives the highest tensile strength of 330 MPa and the hardness of 110HBN. The fractography and morphology are investigated using SEM (scanning electron microscope), resulting in the lowest porosity of 3.21% obtained in the composite material. The tribological behavior was also investigated at the condition of dry Sliding using pin on disc tribometer gives the lowest coefficient friction of 0.31 and the wear rate of 0.0051 mm3/m. The experiment is numerically designed and optimized using the response surface methodology (RSM). The obtained value is predicted and validated using a hybrid approach of deep belief network-reptile swarm algorithm (DBN-RSA). The regression of the parameters is about 99.97% showing that the model is very accurate to the experimental results. The RMSE of the proposed method implies less error and shows the accuracy level of the parameters. The result shows that the designed model is best fitted for the tribological and mechanical properties investigation of metal matrix composite. [ABSTRACT FROM AUTHOR]

The effects of alloy composition (Zn/Mg ratio and Ti content) on the microstructure and properties of Al–3.5Mg–xZn–1.22Cu–0.2Zr–yTi aluminum alloy were studied in this paper. The results show that after solution treatment at 450°C × 2h + 460°C × 2h + 470°C × 2h + 475°C × 2h, when the Zn/Mg ratio of the alloy increases from 3.55 to 3.85, the grain size of the alloy increases, the insoluble phase increases, the dislocation decreases, and the intergranular corrosion resistance decreases gradually. Under the condition of T6 aging, the hardness and electrical conductivity of the alloy decreased at first and then increased, and the compressive strength at room temperature also decreased at first and then increased, and the hardness and compressive strength reached the maximum when the Zn/Mg ratio was 3.85. When Zn/Mg is constant, with the increase of Ti content (0–0.88 wt %), the recrystallization degree of the alloy decreases, the insoluble phase increases, the dislocation density and strengthening value gradually decrease, the inter-granular corrosion resistance decreases gradually, and the hardness, electrical conductivity and compressive strength of the alloy decrease gradually under T6 aging. [ABSTRACT FROM AUTHOR]

This study aims to prepare hypereutectic Al–Si alloy cylindrical samples with hard inner surfaces by changing the depth of inner gates in squeeze casting molds. The characteristic parameters (volume fraction and equivalent diameter) of the hard phases (primary Si and Fe-rich phases) and the hardness of the samples were observed. When the depth of the inner gate is 5 mm, there is a radial gradient in the characteristic parameters of the hard phases in the members resulting in surface strengthening of the structural member. However, when the depth of the inner gate is 9 mm, there is no radial gradient. The mechanisms of achieving surface strengthening in hypereutectic Al–Si alloy cylindrical samples by changing the rheological characteristics of semi-solid Al–Si alloy slurries were revealed. [ABSTRACT FROM AUTHOR]

In the present work, the addition effects of nanodiamond (ND) on the microstructure and hardness behavior of interpenetrating phases hybrid Al/Al2O3 metal matrix composites were investigated. The fabrication of the composites was done via a two-step process. In the first step, hybrid Al2O3-ND preforms were prepared, and then molten pure Al alloy was infiltrated into the preforms. The preforms were fabricated by the replica method using a polyurethane foam and an Al2O3-ND slurry with various ND contents (0, 1, 3, and 10 vol%). The preforms were sintered at 1500 °C for 4 h under argon gas protection. Finally, the composites were fabricated by Al melt infiltration into the preforms via the squeeze casting method. The microstructure of the fabricated composites was analyzed using optical and scanning electron microscopes. The hardness of the composites was measured using a Vickers hardness tester. The results of the microstructural evaluations demonstrated a good distribution of ND in the preform. By increasing the ND content from 0 to 10 vol%, the matrix average grain size decreased from 143 µm to 76 µm. The results of the Vickers hardness test showed that increasing the volume percentage of ND increased the composite hardness to 263.8 Vickers at 10 vol%. The two main strengthening mechanisms for these composites are the Orowwn mechanism (volume fraction of ND particles) and the Hal-Petch mechanism (grain size), which affect the hardness behavior. [ABSTRACT FROM AUTHOR]

In the present work, the effect of squeezing at 100 MPa during AZ91 Mg alloy casting has been studied, where the microstructure, texture, and mechanical properties of gravity die-cast (GC) and squeeze cast (SC) AZ91 alloy samples have been compared. Also, the effect of the combined addition of calcium (Ca) and strontium (Sr) on microstructure and mechanical properties of AZ91 alloy fabricated by SC has been investigated. The SC AZ91 alloy samples exhibited weaker texture than that of GC AZ91 alloy with a reduction in maximum texture intensity. The squeeze casting resulted in the refinement of the secondary phase (β-Mg17Al12) in the microstructure by reducing its segregation at the grain boundaries. The volume fraction of β-Mg17Al12 was more suppressed with Ca and Sr alloy addition due to the formation of new Al2Ca and Al4Sr intermetallics. The tensile properties of SC AZ91 samples were found to be better than that of GC AZ91 samples. Further improvements in mechanical properties were obtained after alloying with Ca and Sr, and the best combination of all tensile properties was obtained at (1% Ca + 0.9% Sr) addition. Higher Sr addition than 0.9% Sr degraded the strength as it induced brittleness in the material. [ABSTRACT FROM AUTHOR]

In this study, an enclosed cooling slope channel (ECSC) was used to produce a semi-solid slurry of the 7075 aluminum alloy. The effects of the pouring temperature and the rate of cooling water on the microstructure of the semi-solid slurry were studied. The microstructure, solidification behavior, mechanical properties, and fracture mechanism of rheological squeeze casting (Rheo-SC) and liquid squeeze casting (LSC) samples were compared. The results indicate that lowering the pouring temperature and increasing the rate of cooling water can refine the crystals of the semi-solid slurry. The best process is a pouring temperature of 670 °C and a rate of cooling water of 200 L/h. The microstructure of the LSC samples was made up of coarse dendritic crystals, but the microstructure of the Rheo-SC samples was made up of almost spherical primary α1-Al and refined secondary α2-Al under this method. The ultimate tensile strength, yield strength, and elongation of the Rheo-SC samples were 238 MPa, 151 MPa, and 5.2%, respectively, which were 10%, 10.5%, and 44.4% higher than those of the LSC sample. The key factor contributing to the increased performance of the Rheo-SC samples is the combination of decreased casting flaws, strengthened grain refinement, and improved segregation. [ABSTRACT FROM AUTHOR]

In this study, concurrent enhancements in both strength and ductility of the Al-2Li-2Cu-0.5Mg-0.2Zr cast alloy (hereafter referred to as Al-Li) were achieved through an optimized forming process comprising ultrasonic treatment followed by squeeze casting, coupled with the incorporation of Sc. Initially, the variations in the microstructure and mechanical properties of the Sc-free Al-Li cast alloy (i.e., alloy A) during various forming processes were investigated. The results revealed that the grain size in the UT+SC (ultrasonic treatment + squeeze casting) alloy was reduced by 76.3% and 57.7%, respectively, compared to those of the GC (gravity casting) or SC alloys. Additionally, significant improvements were observed in its compositional segregation and porosity reduction. After UT+SC, the ultimate tensile strength (UTS), yield strength (YS), and elongation reached 235 MPa, 135 MPa, and 15%, respectively, which were 113.6%, 28.6%, and 1150% higher than those of the GC alloy. Subsequently, the Al-Li cast alloy containing 0.2 wt.% Sc (referred to as alloy B) exhibited even finer grains under the UT+SC process, resulting in simultaneous enhancements in its UTS, YS, and elongation. Interestingly, the product of ultimate tensile strength and elongation (i.e., UTS × EL) for both alloys reached 36 GPa•% and 42 GPa•%, respectively, which is much higher than that of other Al-Li cast alloys reported in the available literature.

In this study, near-liquidus squeeze casting AZ91D alloy was used to prepare differential support, and the microstructure and mechanical behavior under different applied pressure were investigated. Under the preset temperature, speed, and other process parameters, the effect of applied pressure on the microstructure and properties of formed parts was analyzed, and relevant mechanism was also discussed. The results showed that the ultimate tensile strength (UTS) and elongation (EL) of differential support can be improved by controlling real-time precision of the forming pressure. The dislocation density in the primary phase increased obviously with the pressure increasing from 80 MPa to 170 MPa, and even tangles appeared. When the applied pressure increased from 80 MPa to 140 MPa, the α-Mg grains were gradually refined, and the microstructure changed from rosette to globular shape. With increasing the applied pressure to 170 MPa, the grain could not be further refined. Similarly, its UTS and EL gradually increased with the applied pressure increasing from 80 MPa to 140 MPa. With increasing to 170 MPa, the UTS tended to be constant, but the EL gradually decreased. In other words, the UTS (229.2 MPa) and EL (3.43%) of the alloy reached the maximum when the applied pressure was 140 MPa, and the comprehensive mechanical properties were the best. [ABSTRACT FROM AUTHOR]

Squeeze casting is a well-established and reliable process for fabricating high-integrity metallic alloys, bimetals, and composites. The quality and high performance of squeeze cast components are dependent on optimum casting conditions. Inappropriate selection of parameter values may adversely affect the quality of the casting. The squeeze cast components are generally subjected to secondary processing such as heat treatment, extrusion, and other bulk deformation processes to improve the microstructural features and mechanical properties. Heat treatment further refines the grains and reduces porosity, consequently improving tensile strength, and hardness; however, ductility decreases. This paper provides a comprehensive review on studies concerning the influence of processing parameters on porosity, density, percentage elongation, strength, hardness, wear, and fracture of squeeze casting alloys, aiming to provide sufficient information on the squeeze casting process and the effects of processing parameters on product quality. [ABSTRACT FROM AUTHOR]

In this study, the heat treatment process of a high-chromium cast iron (HCCI) alloy prepared via 128 MPa squeeze casting at different subcritical quenching temperatures was investigated. The results showed that subcritical heat treatment can change the martensite content, the carbide type and size of the squeeze casting HCCI microstructure. Furthermore, it was revealed that the subcritical quenching heat treatment can improve the hardness of the liquid-forged HCCIs. When the quenching temperature increased from 500 °C to 530 °C, the hardness of the alloy increased significantly, reaching a maximum value of 57 HRC. Thereafter, if the temperature continued to rise to 630 °C, the hardness decreased rapidly. For impact toughness, when the quenching temperature was 500 °C, the toughness of alloy increased by 0.9 J/cm2 than that of the no heat treatment group. If the quenching temperature continued to increase, the toughness was reduced. Taking hardness and toughness into account, the microstructure evolution diagram of the optimal process-500 °C subcritical quenching process was established, various characterisation techniques were used to gain insights into the optimal heat treatment process. Compared with high temperature heat treatment, subcritical heat treatment can improve the performance of the HCCI alloy and reduce costs. [ABSTRACT FROM AUTHOR]

The current study investigated the effect of adding La and Nd on the microstructural evolution and corrosion response of AZ91 magnesium alloy. Mg–Al–Zn–La–Nd alloys with different WLa/WNd ratios were developed by the squeeze casting process. Typical characterization was conducted using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning Kelvin probe force microscopy (SKPFM), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) tests to analyze the effect of WLa/WNd on the corrosion performance of Mg–Al–Zn–La–Nd alloys. AZLN alloys showed better corrosion resistance, mainly due to the microstructure refinement of RE addition and the protective effect of RE oxide films. In addition, the acicular Al11RE3 phase acts as a barrier against corrosion and is more effective than the granular Al2RE phase. As a result, the Mg–Al–Zn–La–Nd alloy with a WLa/WNd ratio of 3/2 is more corrosion resistant than other alloys due to its finer morphology and more uniform distribution of secondary phases. [ABSTRACT FROM AUTHOR]

In this research, aluminum matrix composites reinforced with continuous carbon fibers (CFs) were fabricated using A356 aluminum alloy and PAN-based CFs by squeeze casting. For this purpose, CFs were first coated with a nickel layer using the electroless method and then the microstructure of the nickel–phosphorus (Ni–P) electroless coating was investigated. In the next step, composite samples reinforced with volume fractions of 5, 10, and 15 vol.% CFs coated with Ni–P coating were fabricated by squeeze casting at 60 MPa, and then microstructure and mechanical properties were examined. The results of the bending test on the composite samples indicated that the nickel coating had a significant effect on the flexural strength of the composite and increased the flexural strength by up to 30%. In addition, with the increase in the volume percentage of the fibers, the hardness of the samples increased while both the wear rate and the coefficient of friction decreased. Moreover, the best wear resistance was observed in the sample containing 15 vol.% as-coated carbon fibers. The Ni coating led to the formation of a mechanically mixed layer (MML) containing a fine mixture of metallic oxides and carbon thus enhancing the wear resistance. [ABSTRACT FROM AUTHOR]

In this paper, ZL205A (AlCu5Mn alloy) castings were prepared by squeeze casting. The effects of solution and ageing treatment on the microstructure and mechanical properties of ZL205A castings were studied by metallography, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and mechanical properties tests. The results showed that most of the θ(Al2Cu) and T(Al12CuMn2) phases in squeeze-cast ZL205A dissolved into the α(Al) matrix after solution treatment for 15 h. The fine precipitates gradually increased with the ageing time. The ultimate tensile strength of the specimen aged for 6 h was the highest of 467 MPa and the elongation was up to 15.1%, showing good comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

In this work, the 4 wt.% TiB2/Al composite with non-dendritic microstructures was fabricated by ultrasonic-assisted squeeze casting. The microstructures and mechanical properties of as-cast composites solidified under different casting temperatures were studied. Furthermore, a short process semisolid billet preparation route was developed, and hereby the thixoformability of as-cast composite was analyzed via thixoforging a complex-shaped part. The semisolid microstructure evolution, microstructures, and mechanical properties of thixoforged part were investigated. Results showed that the decreasing of the casting temperature was helpful to generate non-dendritic microstructures and improve the mechanical properties. When casting billet was partially remelted at 628 °C for 5 min by induction heating, the ideal semisolid billets consisting of fine and near-spherical solid grains were generated. The average grain size and shape factor were 66.9 μm and 0.85, respectively. A kind of connecting rod with favorable forming quality was successfully forged from the as-cast billet based on short process thixoforging. The yield strength, ultimate tensile strength and elongation of thixoforged part (I-beam region) were 160.81, 317.21 MPa and 19.14%, respectively, which were improved by deformed solid grains, refinement of TiB2 particles and eutectic phases compared with the casting billets. [ABSTRACT FROM AUTHOR]

In this paper, the refinement effect of Al-5Ti-0.2C refiner on Al-Zn-Mg-Cu alloys was first investigated, and then the effects of three forming processes, i.e., Gravity Casting (GC), Squeeze Casting (SC), and Squeeze Casting after Ultrasonic Treatment (UT-SC), on microstructure and properties of Al-Zn-Mg-Cu alloys were studied. The results show that the refining effect of Al-5Ti-0.2C refiner is obvious; first, the average grain size of the alloy decreases and then increases with the increase in Ti content from 0.15 wt.% to 0.3 wt.%. The optimal amount of added Al-5Ti-0.2C is 0.2 wt.% Ti content. The good refining effect is attributed to the formation of TiC particles and Al3Ti compounds by the refiner, which can all be the nucleus of solidification. The poor refining effect when the Ti content was more than 0.2 wt.% is due to the formation of coarse Al3Ti particles. The results of three forming processes that cast Al-Zn-Mg-Cu alloys under the addition of Al-5Ti-0.2C with 0.2 wt.% Ti content show that the mechanical properties under the UT-SC process are the best; the tensile strength in the as-cast state reaches 367 MPa, and the elongation is 3.84%. The effect of tiny TiC particles in the refiner on the microstructure and properties of Al-Zn-Mg-Cu alloys is also discussed. [ABSTRACT FROM AUTHOR]

The present study was conducted to examine the physical, metallurgical, mechanical, and tribological behaviors of A356 alloy reinforced with fly ash (5, 10 wt%), and SiCp (2.5 wt%) hybrid composites. Three hybrid composites were synthesized and consolidated through a stir cum squeeze cast technique followed by solution treatment and aging. X-ray diffraction and microstructural evaluations were performed using an optical microscopy and a scanning electron microscopy. The microstructural results revealed pore-free, homogeneous dispersions and effective bonding of reinforcements in the matrix. The experimental bulk density of the A356-10wt% fly ash-2.5 wt% SiC hybrid composite exhibited lower value compared with other samples indicating lighter weight. The same sample produced Brinell hardness number of 90.35 ± 3.80 HB and ultimate strength of 329 MPa which was 1.28 times and 1.14 times higher than matrix respectively. The dry sliding wear test results showed that the wear rate and coefficient of friction started to increase with increasing applied load and sliding speed. The 10 wt% fly ash sample produced lower wear rate 1.42 × 10−3 mg/m at a load 10 N and sliding distance of 1000 m. Finally, the surface worn-out mechanisms were studied using SEM. The developed 10 wt% fly ash-based hybrid composite exhibited improved performances recommending to use in automotive and various structural parts. [ABSTRACT FROM AUTHOR]

This paper carried out numerical simulations of the entire process of rheological squeeze casting of A356 alloy, evaluated the impact of various combinations of forming process parameters on the temperature field, flow field, and solid-phase fraction of A356 semi-solid slurry, and studied the influence of die temperature (°C) and filling speed (mm/s) on the microstructure formation mechanism of A356 alloy rheological squeeze castings. The research revealed that A356 alloy castings with diverse microstructural features can be achieved by solely controlling the rheological squeeze casting process parameters, without the use of additional heterogeneous nucleating agents or heat treatment. Through combined numerical simulation and experimental results, the optimal rheological squeeze casting process parameters were determined: filling speed of 20 mm/s and mold temperature of 350 °C. It was observed that with the simultaneous increase of mold temperature and filling speed, the average equivalent diameter of the α-Al phase significantly increased from 26.18 μm to 44.27 μm, the uniformity of the eutectic structure distribution was greatly improved, and it was also found that the excessively high filling speed is a critical factor contributing to the coexistence of the script-shaped π-Al8FeMg3Si6 phase and the undecomposed the needle-like β-Al5FeSi phase. [ABSTRACT FROM AUTHOR]

The current study focuses on reusing spent catalysts and fly ash, presenting an interesting and intriguing topic for the researchers. The waste catalyst and fly ash from the petroleum and coal industries were initially considered hazardous. One of the most common approaches to recycling spent catalyst and fly ash involves incorporating them into the aluminum matrix to improve the mechanical behaviour for specific applications. This study uses pure aluminum as the matrix material for synthesizing a hybrid composite using an ultrasonic-aided squeeze casting technique. The spent catalyst and fly ah particles were ball-milled before being utilized as reinforcing particles with varying concentrations (2 wt% and 4 wt%) and mean particle sizes of 221.75 nm and 201.25 nm, respectively. The microstructure and mechanical behaviour of the aluminum composites produced using both reinforcements were investigated and compared. The scanning electron microscope (SEM) analysis shows that using ultrasonic treatment in squeeze casting improves the uniform dispersion of the reinforcement nanoparticle. The optical microscope shows that incorporating nanoparticles, coupled with intensive ultrasonic treatment, reduces the grain size of α-Al dendrites. Energy dispersive X-ray analysis (EDAX) and X-ray diffraction (XRD) indicate that the fabricated nanocomposite is free from impurities, contaminants, and oxide formations. The hardness, compressive, and tensile tests were conducted on the prepared aluminum composites. The overall results show that Al+2 wt% spent catalyst+2 wt% fly ash composite improves hardness, tensile, and compressive strength by 98.55 %, 43.24 %, and 29.24 %, respectively, compared to the base pure aluminum. The strength of the aluminum composites has been evaluated using various strengthening mechanism techniques. The strengthening contributions are primarily due to the temperature mismatch between the waste reinforcement nanoparticles and the aluminum matrix. It is well known that metal-based composites strengthen dispersion, in which the dispersed particles hinder dislocation motion and significantly increase the composite strength. [Display omitted] • Aluminum composites were fabricated using two distinct percentages of waste fly ash and spent catalyst nanoparticles. • Impact of waste nanoparticles in the aluminum composite and the mechanical behaviour was evaluated and compared. • Hardness, compressive and tensile strength of the 2wt% composites with UV increased by 98.55%, 43.24%, and 29.24%, respectively. [ABSTRACT FROM AUTHOR]

The WE43 magnesium alloy was prepared by squeeze casting, and the influence of squeeze casting parameters on mechanical properties and corrosion resistance was studied and compared with gravity casting. The gravity cast WE43 alloy shows uneven grain size distribution, and some grains even greater than 90 µm. While, the grain size of the squeeze cast WE43 alloy is mainly distributed in 20–50 µm. The Mg12Nd2Y phase morphology changes from large lamellar to strips after squeeze casting, whereas Mg24Y5 phase exhibits no obvious change. The yield strength, tensile strength, and elongation of the gravity cast WE43 alloy are 127 MPa, 157 MPa, and 6%, respectively, and 145 MPa, 193 MPa, and 9.1% for squeeze cast alloy. For the squeeze cast WE43 alloy, the average corrosion rate is 0.6056 mm·year−1 according to immersion test results, and according to electrochemical measurements, the corrosion current density is 78.13 µA·cm−2, which is better than that of the gravity cast WE43 alloy. Compared with gravity casting, the grains and second phase of the WE43 alloy by squeeze casting are refined, and the mechanical properties and corrosion resistance are improved. This may expand the applications of the WE43 alloy. [ABSTRACT FROM AUTHOR]

In this study, AZ91/23 vol.% short carbon fiber composite was produced by a squeeze casting technique using a cylindrical pre-form of treated carbon fibers, in which the fibers are randomly oriented in the horizontal plane. Cylindrical specimens (height = 9 mm and diameter = 6 mm) were machined from the as-cast AZ91 matrix and its composite. The full behavior of the produced composite was studied through the test specimens machined in two directions, namely parallel to the reinforced plane (in the radial direction of the cast cylinder) and normal to the reinforced plane (in the axial direction of the cast composite). The microstructures of the produced composite specimens were investigated using SEM equipped with EDS analysis. Density, hardness, compressive, and wear behavior were also investigated. For comparison, the AZ91 matrix was evaluated as a reference. The microstructure of the produced AZ91 matrix alloy and its composite revealed dense materials without casting defects. Both composite specimens show improvement in hardness, compressive strength, and wear properties over the AZ91 matrix. The compressive and wear properties are more fiber orientation-dependent than the hardness results. The parallel composite specimen depicts the highest compressive properties in terms of yield compressive strength (311 MPa) and ultimate compressive strength (419 MPa), compared to that shown by the AZ91 matrix and the normal composite specimen. This improvement in compressive strength was at the expense of ductility. The parallel composite specimen shows the lowest ductility (R = 3.8%), compared to that given by the normal composite specimen (R = 7.1) and the AZ91 matrix alloy (R = 13.6). The wear testing results showed that at the highest wear load of 5 N, the material weight loss of the parallel composite specimen decreases by 44% and 64% compared to the AZ91 matrix and the normal composite specimen, respectively. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the wear and micro hardness of a Ti-6Al-4V matrix reinforced with 10% and 15% tungsten carbide particle (WCp) composite manufactured using the squeeze casting process. Optical microscopy is used to determine the microstructures of the composite. A pin-on-disc wear test equipment and Vickers hardness at atmospheric temperature were used to examine the wear behaviour wear rate, CoF, and micro hardness qualities of primed samples. Loads of 10 N to 80 N, velocities of 4 m/s, and distances of 1000 m to 2000 m are considered for analyzing the wear behaviour of Ti-6Al-4V composites. The wear rate values are 25.683 for 10% WCp, 30.957 for 15% WCp, and 37.683 and 30.957 for 20% WCp. A scanning electron microscope (SEM) is utilized to examine the worn surface of the composites. For 10% WCp, the CoF values are 0.82 and 0.87, and for 15% WC, 0.88 and 0.956. The micro hardness values are 692 VHN for 10% WCp and 835 VHN for 15% WCp. The wear rate, microstructure, SEM images, coefficient of friction, and hardness of TMCs for totaling reinforcing tungsten carbide particle (WCp) possessions were discovered to be improved. [ABSTRACT FROM AUTHOR]

Al-8Zn-2Mg-1.5Cu-0.15Sc-0.15Zr alloy with high-strength performance as well as good castability has been developed. In this study, effects of electromagnetic stirring melt treatment (ESMT) on microstructure and mechanical properties of the alloy in the squeeze casting process were investigated. The results show that solidification structure and mechanical properties are significantly improved by ESMT; compared with the conventional squeeze casting, the average grain size decreases from 112 μm without ESMT to 53 μm with ESMT. Meanwhile coarse primary Al3(Sc, Zr) particles unavoidably occurred in cases without ESMT disappear, and segregation degree of the main elements of Zn, Mg, Cu are greatly alleviated; the tensile strength increases from 590 MPa to 610 MPa, and the elongation increases from 9% to 11%. The structure refinement and homogenization should owe to uniform temperature and composition distribution by ESMT under squeeze casting with rapid solidification. [ABSTRACT FROM AUTHOR]

Mechanical properties and tensile fracture behavior of normal 7075 aluminum alloy produced by rheoforming were investigated. The rheoforming applies limited angular oscillation (LAO) technique for semi-solid slurry preparation and rheological squeeze casting with transverse moving injection feed semi-solid slurry. The microstructures of as-cast rheoformed 7075 alloy are composed of fine spherical α-Al grains with average size of 26 μm surrounded by eutectic mixture. T6 heat treatment (solution treatment for 4 h at 838 K (465 °C) and aging for 12 h at 393 K (120 °C)) causes a slight increase of grain size and the formation of fine semi-coherent precipitation of η′ phase in α-Al matrix. Good elongation to fracture (10.1%, which is quite close to the wrought target (11%)) is obtained for rheoformed 7075 alloy after T6 heat treatment, with average yield strength of 461 MPa and average ultimate tensile strength of 514 MPa. Pores and voids are main defects observed in rheoformed 7075 alloy. The fracture surface of as-cast rheoformed 7075 alloy consists of large and deep dimples showing the growth and coalescence of voids. After T6 treatment, the fracture surface is composed of large dimples, flat areas containing super-fine dimples and tear ridges. Pores are present in the form of large dimples in fracture surface. The crack initiates at pores and propagates by the coalescence of pores and voids. [ABSTRACT FROM AUTHOR]

In this research, 6082 aluminum alloy automotive flange components with complex shape and large wall thickness difference were formed via squeeze casting. The effect of T6 heat treatment process parameters (solution time, solution temperature, aging time and aging temperature) on microstructure and mechanical properties were studied through controlling variable method. The yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) of 6082 aluminum alloy automotive flange components after T6 heat treatment were firstly increased and then decreased with the increasing solution temperature, solution time and aging time, respectively. However, with an increase of aging temperature, YS and UTS were significantly increased, while EL was decreased. The optimal T6 heat treatment process parameters (solution temperature of 525 °C, solution time of 180 min, aging temperature of 185 °C and aging time of 420 min) were obtained. Under the optimal T6 heat treatment process parameters, the YS, UTS, EL were 304.2 MPa, 348.7 MPa and 7.42 %, respectively. The fracture mode is a mixture of ductile and cleavage fracture. After T6 heat treatment, a plethora of tiny precipitates appeared, which included the Al(FeMn)Si phase with a size of about 100 nm and the finer β ″-Mg 2 Si phase. These tiny precipitates lead to lattice distortion to hinder the movement of dislocations and they had a significant strengthening effect on the improvement of mechanical properties. In short, 6082 aluminum alloy automotive flange components produced by squeeze casting after T6 heat treatment has significantly competitive advantages for its outstanding mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, the heat treatment process of a high-chromium cast iron (HCCI) alloy prepared via 128 MPa squeeze casting at different subcritical quenching temperatures was investigated. The results showed that subcritical heat treatment can change the martensite content, the carbide type and size of the squeeze casting HCCI microstructure. Furthermore, it was revealed that the subcritical quenching heat treatment can improve the hardness of the liquid-forged HCCIs. When the quenching temperature increased from 500 °C to 530 °C, the hardness of the alloy increased significantly, reaching a maximum value of 57 HRC. Thereafter, if the temperature continued to rise to 630 °C, the hardness decreased rapidly. For impact toughness, when the quenching temperature was 500 °C, the toughness of alloy increased by 0.9 J/cm2 than that of the no heat treatment group. If the quenching temperature continued to increase, the toughness was reduced. Taking hardness and toughness into account, the microstructure evolution diagram of the optimal process-500 °C subcritical quenching process was established, various characterisation techniques were used to gain insights into the optimal heat treatment process. Compared with high temperature heat treatment, subcritical heat treatment can improve the performance of the HCCI alloy and reduce costs.

The aim of the present work is to examine the influence of processing parameters on fabricated composites of LM25 alloy with SiC particle reinforcement through a squeeze casting technique. The following process parameters, like stirring speed from 550 to 750 rpm, SiCP (4 wt% to 8 wt %), and melting temperatures (from 600 to 700 °C) were employed. Then, the processed composites were subjected to microscopy analysis and mechanical tests to ascertain their metallurgical and mechanical properties. SEM micrographs of an LM 25 composite sample show better bonding of SiC particles with matrix, which is due to homogeneous dispersion of SiC particles in the stir casting process. The maximum tensile strength (211 MPa) and hardness (91 Hv) were achieved on the composite samples with processing parameters of 750 rpm stirring speed, 8% SiC proportions, and 650 °C melting temperature, respectively. From the design of the experiment by the Taguchi method, it is observed that the stirring speed plays a significant role in achieving a better distribution of SiC particles in the composite samples than other parameters like SiC weight ratios and the melting temperature of the alloy.

The effects of the squeeze casting process on the microstructure, mechanical properties and wear characteristics of hypereutectic Al–Si–Cu–Mg alloys have been investigated by optical, scanning and transmission electron microscopy and mechanical property test; the wear behaviour was investigated using a pin-on-disc configuration; alloy ingots were prepared by gravity casting, liquid squeeze casting and semisolid squeeze casting. The results show that the Si phase was refined and the α-Al dendrites transformed to rosette grains after semisolid squeeze casting. The peak intensity of the second phase decreased after extrusion, indicating that extrusion promotes the dissolution of solute elements into the matrix. Among the three casting processes, the alloys formed by semisolid squeeze casting had the best mechanical properties. Tensile strength, elongation and Brinell hardness reached 187.67 MPa, 2.33% and 142.5 HB, respectively. After semisolid squeeze casting, the morphology of the wear surface was flat and the number of spalling pits and furrows is less. Meanwhile, the friction coefficient and wear loss of the alloy sample are minima. Due to the uniform distribution of Si phases and equiaxed crystallization of α-Al phase in semisolid squeeze casting Al–Si–Cu–Mg alloys, the wear resistance is markedly enhanced. [ABSTRACT FROM AUTHOR]

In this paper, ZL205A (AlCu5Mn alloy) castings were prepared by squeeze casting. The effects of solution and ageing treatment on the microstructure and mechanical properties of ZL205A castings were studied by metallography, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and mechanical properties tests. The results showed that most of the θ(Al2Cu) and T(Al12CuMn2) phases in squeeze-cast ZL205A dissolved into the α(Al) matrix after solution treatment for 15 h. The fine precipitates gradually increased with the ageing time. The ultimate tensile strength of the specimen aged for 6 h was the highest of 467 MPa and the elongation was up to 15.1%, showing good comprehensive mechanical properties.

In this study, AZ91/23 vol.% short carbon fiber composite was produced by a squeeze casting technique using a cylindrical pre-form of treated carbon fibers, in which the fibers are randomly oriented in the horizontal plane. Cylindrical specimens (height = 9 mm and diameter = 6 mm) were machined from the as-cast AZ91 matrix and its composite. The full behavior of the produced composite was studied through the test specimens machined in two directions, namely parallel to the reinforced plane (in the radial direction of the cast cylinder) and normal to the reinforced plane (in the axial direction of the cast composite). The microstructures of the produced composite specimens were investigated using SEM equipped with EDS analysis. Density, hardness, compressive, and wear behavior were also investigated. For comparison, the AZ91 matrix was evaluated as a reference. The microstructure of the produced AZ91 matrix alloy and its composite revealed dense materials without casting defects. Both composite specimens show improvement in hardness, compressive strength, and wear properties over the AZ91 matrix. The compressive and wear properties are more fiber orientation-dependent than the hardness results. The parallel composite specimen depicts the highest compressive properties in terms of yield compressive strength (311 MPa) and ultimate compressive strength (419 MPa), compared to that shown by the AZ91 matrix and the normal composite specimen. This improvement in compressive strength was at the expense of ductility. The parallel composite specimen shows the lowest ductility (R = 3.8%), compared to that given by the normal composite specimen (R = 7.1) and the AZ91 matrix alloy (R = 13.6). The wear testing results showed that at the highest wear load of 5 N, the material weight loss of the parallel composite specimen decreases by 44% and 64% compared to the AZ91 matrix and the normal composite specimen, respectively.

Al-8Zn-2Mg-1.5Cu-0.15Sc-0.15Zr alloy with high-strength performance as well as good castability has been developed. In this study, effects of electromagnetic stirring melt treatment (ESMT) on microstructure and mechanical properties of the alloy in the squeeze casting process were investigated. The results show that solidification structure and mechanical properties are significantly improved by ESMT; compared with the conventional squeeze casting, the average grain size decreases from 112 μm without ESMT to 53 μm with ESMT. Meanwhile coarse primary Al3(Sc, Zr) particles unavoidably occurred in cases without ESMT disappear, and segregation degree of the main elements of Zn, Mg, Cu are greatly alleviated; the tensile strength increases from 590 MPa to 610 MPa, and the elongation increases from 9% to 11%. The structure refinement and homogenization should owe to uniform temperature and composition distribution by ESMT under squeeze casting with rapid solidification.

The automotive industry traditionally reduces weight primarily by value engineering and thickness optimization. However, both of these strategies have reached their limits. A 6% reduction in automotive truck mass results in a 13% improvement in freight mass. Aluminum alloys have lower weight, relatively high specific strength, and good corrosion resistance. Therefore, the present manuscript involves manufacturing Al-based alloy by squeeze casting. The effect of applied pressure during the squeeze cast and gravity cast of a novel Al-Si alloy on microstructural evolution, and mechanical and wear behavior was investigated. The results demonstrated that squeeze casting of the novel Al-Si alloy at high-pressure exhibits superior mechanical properties and enhanced wear resistance in comparison to the gravity die-cast (GDC) counterpart. Squeeze casting of this alloy, at high pressure, yields fine dendrites and reduced dendritic arm spacing, resulting in grain refinement. The finer dendrites and reduced dendritic arm spacing in high-pressure squeeze cast alloy than in the GDC alloy were due to enhanced cooling rates observed during the solidification process, as well as the applied squeeze pressure breaks the initial dendrites that started growing during the solidification process. Reduced casting defects in the high-pressure squeeze cast alloy led to a reduced coefficient of friction, resulting in improved wear resistance even at higher loads and higher operating temperatures. Our results demonstrated that squeeze casting of the novel Al-Si alloy at high-pressure exhibits a 47% increase in tensile strength, 33% increase in hardness, 10% reduction in coefficient of friction, and 15% reduction in wear loss compared to the GDC counterpart.

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As the most popular magnesium alloy, AZ91 is desired in the automotive-related manufacturing industry because of its high specific strength and good corrosion resistance. AZ91-based automotive components are made by conventional high-pressure die casting (C-HPDC) and are unable to provide adequate mechanical properties to components with heavy cross sections because of the high level of gas and shrinkage porosity in C-HPDC parts. To expand the usage of AZ91, a replacement for the C-HPDC to minimize the porosity content is needed. In this research, Mg alloy AZ91 with a cross-sectional thickness of 10 mm was squeeze cast (SC) under an applied pressure of 90 MPa. A counterpart was made by C-HPDC for comparison with SC AZ91. The porosity of the SC and C-HPDC AZ91 specimens was evaluated by optical microscopy and density measurements. The SC AZ91 was almost pore free, whereas the counterpart had a porosity of 3.57%. Microstructural analyses by scanning electron microscopy showed that the SC and C-HPDC AZ91 contained phases of primary α-Mg, β-Mg17Al12 eutectic and Al-Mn intermetallic. Tensile testing indicated that the ultimate tensile strength and elongation (ef) of the SC alloy were 171.7 MPa and 3.0%, which resulted in improvements of 33 and 77% compared with those of the C-HPDC counterpart. The strain-hardening rate and tensile toughness of the SC AZ91 during deformation were higher than those of the HPDC specimen. SEM fractography revealed characteristics of plastic deformation on the flat fractured surface of the SC AZ91, whereas brittle fracture prevailed on the HPDC counterpart. [ABSTRACT FROM AUTHOR]

Semi-solid AZ91D magnesium alloy billets were prepared by near-liquidus heat holding. Semi-solid squeeze casting was conducted at 575, 585 and 595 °C, respectively, with 1 mm·s-1 squeeze speed. The semisolid squeeze casting AZ91D samples were heat treated by T4 (solution at 415 °C for 24 h) and T6 (solution at 415 °C for 24 h + 220 °C for 8 h) processes, respectively. The microstructure and mechanical properties of the alloy in different states were investigated by means of OM, SEM and tensile testing machine. The results show that compared to as-cast alloy, the grain size of the semi-solid squeezed AZ91D decreased significantly, and with the increase of semi-solid squeeze temperature, the grain size of AZ91D increased. The grains of the alloy were refined by T4 treatment, and further refined by T6 treatment. T6 treatment greatly improved the tensile strength, elongation, and hardness, but did not significantly improve yield strength. After 575 °C squeeze casting and T6 treatment, the ultimate tensile strength (UTS) reached 285 MPa, the elongation reached 13.36%, and the hardness also reached the maximum (106.8 HV), but the yield strength (YS) was only 180 MPa. During the process of semi-solid squeeze casting and heat treatment, the matrix grain was refined and a large number of precipitated and secondary precipitated phases of Mg17Al12 appeared. Both the average size of matrix grain and secondary precipitated phase decreased, while the volume fraction of secondary precipitated phase increased. All these resulted in high tensile strength, elongation and hardness. [ABSTRACT FROM AUTHOR]

Effects of squeeze casting (SQC) parameters, including squeezing pressure, superheats of liquid metal and die preheating temperature on microstructure characteristics and mechanical properties of A390 aluminum alloy, were evaluated using L9 design based on Taguchi method. Squeeze casting was performed by a 25-ton hydraulic press, and all of the parameters were evaluated at 3 different levels: the squeezing pressure was at 60, 90 and 120 MPa, the superheat of the liquid metal was at 50, 100 and 150 °C and the die preheating temperature was at 200, 250 and 300 °C. The microstructure characterization was also performed using optical microscopy image analysis and scanning electron microscope (SEM). Tensile and Brinell test methods were applied for measuring ultimate tensile strength, yield strength, elongation and hardness. The results showed that the SQC process modified cast microstructure and improved mechanical properties of the alloy. In addition, the variations of the SQC parameters, specially the squeezing pressure, have significant effects on the size and volume fractions of the primary silicon, eutectic cells and the mechanical properties. According to the results, increase in squeezing pressure from 60 to 120 MPa within the tested range leads to primary silicon area decrease by 48% and silicon eutectic decrease by 44.4%; however, applied pressure did not have any significant effects on morphology of phases. On the other hand, superheating over 100 °C and die preheating at 200 °C had significant effects on the final result. It is clearly observed that rising pressure to 90 MPa consequently increases the tensile strength, elongation and hardness. But increasing the pressure to over 90 MPa did not have any significant effects on the final result. [ABSTRACT FROM AUTHOR]